1. Field of the Invention
The present invention pertains to a gun control system for use with a rotatable gun, and more particularly, it pertains to an apparatus for maximizing the field of fire of a rotatable gun by automatically controlling its movement when it is near a rotative position where either firing or movement is forbidden.
2. Description of the Prior Art
Gun carrying vehicles, such as armored tanks, carry a gun on a turret which is mounted on a deck atop the vehicle and which can be rotated to move the gun in an azimuthal direction to aim the gun in any direction from the vehicle. In addition to moving in an azimuthal direction the gun can typically be elevated through a predetermined acute angle above the horizontal position of the deck. Positioned at several locations about the turret are various types of barriers, such as antenna mounts, personnel hatches and cargo hatches, which could be struck by the moving gun barrel unless the gun operator visually avoids them or a control system is provided for automatically checking the position of each barrier relative to the position of the gun and for taking over the control of the gun when it is near a barrier so that it will not strike the barrier. It is important that the control system operate in a manner such that the gun is left in the control of the operator for the maximum period of time so as to permit maximum firing but at the same time insure against collisions with the barriers.
The rotational movement of the gun turret and the elevation of the gun are usually controlled by a hydraulic system which provides the power for these movements. Electrical signals are provided to a plurality of hydraulic valves which operate hydraulic motors to provide the separate movements of the gun and turret. A finite amount of time is required to energize each of these valves and to operate the hydraulic motors to raise the gun or to stop rotation of the turret. Thus, if the turret is rotating and the gun is approaching one of the barriers on the deck of the vehicle, a signal to raise the gun must be provided a certain amount of time before the gun reaches the barrier. When the turret is moving at a rapid rate this signal must be provided earlier than it need be if the turret is moving at a slow rate in order for the gun to be elevated far enough to clear the barrier. In the prior art gun control systems means were provided for automatically elevating the gun as it neared a barrier so that it would not hit the barrier but there were no means provided for detecting the speed of the gun and for using this information to determine the particular point at which the gun must be raised in order to clear the barrier at the given speed of rotation of the turret. Thus, the maximum rotational speed of the turret was used to determine the point at which the gun must start moving upward in order to clear the barrier. This meant that the gun moved upwardly (and thus off the target) much sooner than was necessary when the turret was moving the gun at a slow rate of speed.